Annual report pursuant to Section 13 and 15(d)

Stock Grants to Employees (Detail)

v3.21.2
Stock Grants to Employees (Detail)
$ / shares in Units, shares in Thousands, $ in Thousands
1 Months Ended 12 Months Ended
Oct. 16, 2020
shares
Sep. 30, 2020
shares
Jul. 31, 2020
USD ($)
shares
Jan. 28, 2020
shares
Dec. 24, 2019
item
shares
Sep. 30, 2020
$ / shares
shares
May 31, 2021
USD ($)
shares
May 31, 2020
USD ($)
shares
May 31, 2019
USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Number of executives | item         2        
Stock-based compensation | $     $ 1,600       $ 10,429 $ 6,548 $ 3,388
Common Stock                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Stock issued for incentive compensation and tendered for income tax , shares     300   400   323 380  
Treasury Stock                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Stock issued for incentive compensation and tendered for income tax , shares     200   100   157 127  
Executives                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Stock option granted, Shares           3,350      
Performance Shares [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Stock units granted, shares       11,700          
Award vesting period       6 months          
Performance Shares [Member] | Executives                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Stock units granted, shares   4,350       4,350      
Stock Options | Executives                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Stock option granted, Shares   3,350              
Award vesting period   3 years       3 years      
Restricted Stock Units (RSUs) [Member]                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Stock units granted, shares 200                
Award vesting period 3 years                
Restricted Stock Units (RSUs) [Member] | Executives                  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]                  
Stock units granted, shares   1,120       1,120      
Award vesting period   3 years       3 years      
Units granted, grant date fair value | $ / shares           $ 3.12